We are continuing our studies on the nature of the blood-ocular barrier and the blood-brain barrier and on the physiological and pathological factors that control and/or alter the chemical composition of intraocular and cerebrospinal fluids. Over the next five years we will focus on a better definition of the prostaglandin transport process and on experimental and pathological factors that affect the chemical composition of intraocular fluids. The mechanism and specificity of prostaglandin transport will be studied in vitro using 3H-prostaglandin uptake by anterior uvea, choroid plexus and kidney cortex. Transmembrane prostaglandin transport will be studied on bladder-like preparations of the rabbit vagina or on the membrane-like preparation of the anterior uvea. We will also study the effects of systemically administered prostaglandin transport inhibitors on the passage of PGs across the blood-ocular and blood-brain barriers and on systemic prostaglandin metabolism and excretion. The effects of experimental uveitis (induced by endotoxin, foreign proteins, nitrogen mustard or x-ray) on the chemical composition of IOFs, and on the transport capacity of the ciliary processes and pigment epithelium will be investigated.